This paper reports on previously undescribed dentofacial features a child suffering from Glycogen-Storage Disease type III with hepatomegaly and hypertransaminasemia with muscular involvement. Deficient craniofacial development, reduced width of the upper jaw resulting in posterior cross-bite, and taurodontism of the primary dentition were found. Pathogenetic basis for craniofacial abnormalities is discussed. Cooperation between pediatricians and pediatric dentists is strongly recommended for an early diagnosis and treatment of the dentofacial defects of the syndrome.